How fast is your GT40? - Page 2

Paul Thompson 'Hooligan' · 01-24-07, 05:00 AM

Correct Martin - he posted an 11.83 at 116 in 2004. Rodger is the only other 40 in the UK that I know of to have officially posted sub 12s, an 11.99? in 2005... (a visit to Santa Pod might prove otherwise...

)

I'm visiting Roy Friday so I'll get the 'Facts' re the 1/10 model and 30KW fan - and hopefully some pics.....

BruceLambo · 01-24-07, 05:25 AM

Paul, what is Roy using for a gearbox in his Mk1 ??

John W · 01-24-07, 05:59 AM

And a further question, what 'softish slicks' does the car run ?
I assume they aren't road legal

The popular tyre for track days in the Audi/Porsche arena seems to be Yokohama A008s, but not sure they are available in GT40 sizes...

Chris_K · 01-24-07, 06:19 AM

I don't know what all the fuss is about. I topped mine out around 85 on the same day I picked it up:

Don't notice that trailer there...

John W · 01-24-07, 10:14 AM

but was that mph or kph Chris

Gary Kadrmas · 01-24-07, 10:20 AM

Chris,

I see you are getting ready for a Bonneville Salt Lake run. That is 200 MPH tape on the front, right?

Gary

Gary Kadrmas · 01-24-07, 10:36 AM

In addition to the questions GT40 NZ posted...............

What speeds in gears are you guys turning? If you post your information, please list what kind of transaxle you are using, your ring and pinion ratio, tire diameter, and the RPM the MPH was acheived.

Speed in gears, speed in gears. Has a nice ring to it, don't ya think?

Gary

Paul Thompson 'Hooligan' · 01-25-07, 07:36 AM

Hi Guys

The Trans is the usual Renault 21Turbo Box - with all quaife internals - i.e. Single piece input shaft with longer 1st/2nd and a Quaife ATB Diff. Diff Ratio is 3.44 - 5th I think is about 0.76?? (will check at weekend).

Road tyres used for high speed were Pirelli - 26.5" Dia? - P7s..?

For standing quarters and sprints - are 25.0/10.0/15 AVON soft slicks - usually found on the big single seaters - about 23.5" sia i think? They are a bit too soft for continued circuit work and will cook if continually pushed hard - good for a couple of fast laps - even from cold, but then you have to ease off a bit.

The car with Steel 302 4-bolt motor would pull happily to 8K. I've logged and passengered whilst tuning and Roy has pulled off in second, accelerating up to 7990rpm in second before pulling 3rd - and believe me - it sounded great - even with earplugs! We also used to use 7800rpm as a limit at Lhergy Frissel Isle-Of-Man Hill Climb - just awesome..!!

With the alloy 347 we only ever managed about 6000-6200rpm - just kept going flat - something the larger injectors were resolving, however as many know, that motor has sadly been mothballed due to a cracked block. (RIP

) It did however really have buckets of torque which meant we generally didnt change down so much, we'd pull 4th all through Lavant corner at Goodwood on slicks - or 3rd on the Pirelli's. A lap of Goodwood from the Chicane on slicks became 3rd-4th-5th-4th-5th-4th-3rd (6 shifts) and on road Pirelli's, the whole lot could be done in 3rd/4th (4 shifts).

I have some speed in gears data somewhere - in fact I'm sure I posted some years back relating to runs and gearchanges at Brighton Speed Trials - Search and you may find it, if not I may be able to dig it out (actually I'm thinking it might have been a Club Mag article I wrote) - I'll look over the weekend to see if I can find it and post.

I'm busy sorting an i/f to add HIDs to a Mustang at the moment, - it normally drives with daylight running lights (yuk) which I need to disable/ignore as the HIDs go beserk if you try to modulate their supply voltage.... so I'll post again over the weekend after visit to Roy's....

Gary Kadrmas · 01-26-07, 10:41 AM

Paul,

Looks like most GT40 drivers never look at their speedometers, huh?

Gary

Ron Earp · 01-26-07, 11:21 AM

I doubt it works or is accurate Gary. I've been a good number of 40s and haven't found many with speedos that are accurate. I'm sure Paul can tell you speeds from data though, I think they hit a very respectible number in the standing mile and have the video footage of that on You Tube as well as the GTD club site.

Ron

Ian Anderson · 01-26-07, 12:12 PM

Ron

all recent builds have to have accurate speedo
The SVA tests at 30, 50 and70mph and you are allowed to overread 3% I believe and not allowed any underread.

The test is done on rollers with the front wheels chocked - he did mine in 3rd gear and at 70 it sounded great from outside the car (Just before it failed the noise test)

Ian

Ron Earp · 01-26-07, 12:19 PM

Good to know. That isn't checked in the US at any point in the process. Also people might do a lot of things after SVA such as fit slicks, different wheels tires, etc. Maybe Roy/Paul's is spot on, I was merely offering up a possible explination from what I've seen in the US and abroad.

I wish we had a national SVA type thing here as it'd get away from all the dang state problems with self built cars which every car on this forum will fall under; GT40s as complete rollers to a home built chassis and home made body.

Best,
Ron

Howard Jones · 01-26-07, 11:36 PM

I've had mine to 6000RPMS in 4th right at the brake point for turn 1 at thunderhill. The math makes that at about 140. I don't think I've had it any faster in 5th on the road but the math puts top end in 5th (6KRpms) at 170 and change. Much too dangerious for the public road. Look at the speedo at 150MPH? Are you nutts?

By the way my speedo is dead right at 80MPH. CHP told be so. Expensive speedo calibaration.

Noise test? Noise test! I don't got to do no stinking noise test senior!